Micro-miniature optical projectors are used in a variety of applications. For example, such projectors may be used to cast a pattern of coded or structured light onto an object for purposes of 3D mapping (also known as depth mapping). In this regard, U.S. Pat. No. 8,150,142, whose disclosure is incorporated herein by reference, describes an apparatus for mapping an object. The apparatus includes an illumination assembly, which includes a single transparency containing a fixed pattern of spots. A light source trans-illuminates the single transparency with optical radiation so as to project the pattern onto the object. An image capture assembly captures an image of the pattern that is projected onto the object, and a processor processes the image so as to reconstruct a three-dimensional (3D) map of the object.
PCT International Publication WO 2008/120217, whose disclosure is incorporated herein by reference, describes further aspects of the sorts of illumination assemblies that are shown in the above-mentioned U.S. Pat. No. 8,150,142. In one embodiment, the transparency comprises an array of micro-lenses arranged in a non-uniform pattern. The micro-lenses generate a corresponding pattern of focal spots, which is projected onto the object.
U.S. Pat. No. 8,749,796, whose disclosure is incorporated herein by reference, describes integrated pattern generators in which laser diodes (such as VCSELs) are arranged in a pattern that is not a regular lattice. Optics may be coupled to project the pattern of light emitted by the elements of a laser diode array into space as a pattern of corresponding spots, wherein each spot contains the light emitted by a corresponding laser diode in the array. In some embodiments, a DOE creates multiple replicas of the pattern, fanning out over an expanded angular range.